This invention relates to an air filtering system, and more particularly, to a system in which the filter media can be easily and economically replaced
Businesses which release small amounts of volatile organic compounds, e.g. solvents, into the atmosphere, such as body shops with paint spray booths, have not previously been subject to many local, state and federal emissions regulations. Recently, however, laws have been enacted which require businesses of this type to reduce their release of volatile organic compounds into the atmosphere.
The most common strategy for disposing of volatile organic compounds is incineration. Incineration is not a desirable alternative for use with small paint spray booths because the solvent laden air they produce has a relatively low concentration of volatile organic compounds. It is not economical to operate an incineration system when these compounds are found in low concentrations. Incineration systems are also designed to operate 24 hours a day, whereas automobile body shops are only open for 8 to 10 hours a day. Moreover, incineration systems can be extremely expensive.
Activated carbon and other filter media have been used for a number of years to adsorb volatile organic compounds. Filter media of this type, however, must be regenerated from time to time in order to maintain its effectiveness in adsorbing these compounds. Regeneration of the filter media can either be accomplished within the filter system, or the filter media can be removed and replaced, the removed media then being taken elsewhere for regeneration There is, however, no system that presently exists which satisfies the requirements of small businesses like automobile body shops.
Regeneration of the filter media within the filter systems requires the use of extremely expensive equipment. Such a system is described in U.S. Pat. No. 4,689,054. A system of that type only becomes economical when huge volumes of solvent laden air are filtered. Automobile assembly plants and the like are generally the only operations large enough to justify such a system.
Systems in which the filter media is removed and replaced have not previously been designed to adequately satisfy the needs of small body shops with paint spray booths. The filter media in prior art systems is generally kept in removable cells or cartridges which are extremely bulky. Even relatively small filter systems may require many of these cells totaling up to 2,000 pounds of filter media. Thus, removing these filter cells can be a difficult, expensive and time consuming operation.
Generally, paint spray booths exhaust solvent laden air out through their roofs. Therefore, any filter system designed for use with existing structures may have to be located on a roof or at another poorly accessible location. The location of these systems may further exacerbate the problems associated with replacing these filter cells. Thus there remains a need for a filter system for producers of small amounts of volatile organic compounds where the filter media can be easily removed and replaced.
The temperatures inside a filter unit may reach extremely high levels. If the filter media becomes too hot, it will begin to desorb, or release into the atmosphere the compounds which have already been adsorbed. There is, therefore, a need for a filter system which can automatically cool the filter media when temperatures inside the system near desorption levels